Recently, patent foramen ovale (hereinafter referred to as PFO) has been identified as a cardiac factor in strokes and migraines. The PFO is a symptom in which the oval foramen (foramen ovale) for shortcircuiting blood between the left and right sides in the heart in the fetal period of a person's life remains even after the person has gown up. It is said that 20-30% of grown-up people have this disease.
The foramen ovale occurs at a septum secundum (Septum Secundum, hereinafter, referred to as atrial septum secundum) of the heart. The pressure on the left atrium side normally exceeds the pressure on the right atrium side in the heart and so the foramen ovale is occluded by a septum primum (Septum Primum, hereinafter, referred to as foramen ovale valve). However, when the pressure on the right atrium side exceeds the pressure on the left atrium side on a strain occasion (for example, when coughing, when holding on) or the like, the foramen ovale valve opens to the left atrium side and blood can flow from the right atrium side (venous side) into the left atrium side (arterial side). When a thrombus is included in this blood, the thrombus is shifted from the venous side to the arterial side, flows in a route of left atrium→left ventricle→aorta→brain, and can become a factor for a stroke, migrane or the like.
To treat such a disease, a treatment by a percutaneous catheter procedure is considered to be a desirable method if the same effect as an open heart surgery can be obtained.
A device performing a closing technique using the percutaneous catheter can be used in the case of closing defects such as a congenital atrial septal defect indwelled (ASD), a PFO, a ventricular septal defect (VSD) and a patent ductus arteriosus (PDA). A device used in the past is a device sandwiching the foramen ovale valve and the atrial septum secundum by using disk-shaped membranes or anchor members for closing the defect and these are indwelled in the body.
The membranes or anchor members are foreign substances for a human body and moreover, a thrombus can relatively easily be attached. In particular, when a thrombus attaches to a disk-shaped membrane or the like on the left atrium side, this flows and there is a possibility that it becomes a cause of a stroke, and there is also a fear that a foramen ovale valve of a thin wall thickness is broken. In addition, these members are not position-fixed in a state of being sandwiched and there is also a possibility of causing a positional displacement.
Consequently, recently, there has been proposed a PFO closing device described in International Application Publication No. WO2004/086944 A2 (Patent Document 1) (see summary, FIG. 10 and the like). This PFO closing device is a device in which an apparatus is inserted into the foramen ovale from the right atrium toward the left atrium, a foramen ovale valve is pulled to the foramen ovale so as to close it and the tissue is fused by applying electric energy. However, the foramen ovale, the foramen ovale valve and the atrial septum secundum are different not only in terms of sizes (small/large) but also in terms of thicknesses, shapes, etc. Depending on the individual and according to circumstances, the size or the like of the apparatus may be restricted a lot. Also, even on an occasion when the procedure is performed, there is a fear that it becomes difficult to pull various forms of foramen ovale valves to the foramen ovale at anytime and with reliability.
Consequently, as shown in Japanese Patent Application No. 2006-47636 (Patent Document 2) (see summary, FIG. 10 and the like), a PFO closing device proposed by the applicant here is constructed so that the foramen ovale valve and the atrial septum secundum are sandwiched by a pair of electrodes and the tissue is fused by applying electric energy from both the electrodes. This PFO closing device uses a clamper in which a stick portion and a sandwich member are composed of a pair of electrodes and with respect to one of them, the stick portion composed of a needle electrode is stuck into the foramen ovale valve. Thereafter, the foramen ovale valve and the atrial septum secundim are sandwiched with respect to the sandwich member which is the other electrode, the biological tissue is applied with electric energy, and the fusion is carried out. If this PFO closing device is used, foreign substances are not indwelled in the body, the construction becomes relatively simple, the procedure is comparatively easy and the foramen ovale valve and the atrial septum secundum can be fused with relative certainty.
However, this device is provided with a guiding catheter on the outside of a fine catheter, and the fine catheter is used by being stored in the guiding catheter. For the sake of attempting simplification of the operation, the stick portion which easily injures the blood vessel is provided position-fixedly at the distal tip of the fine catheter and there is employed a construction in which only the sandwich member moves with respect to the fine catheter, so that the sticking by the stick portion must be executed by moving the fine catheter in the guiding catheter and therefore, there is a drawback of insufficient degree of freedom for selecting the sticking position.
In particular, the sticking (puncture) operation is performed in a state in which the stick portion protrudes from the distal tip of the guiding catheter and by sticking the foramen ovale valve while moving the whole catheter forward and backward, so that the sticking position will be on an extension line of the catheter axial line (axis) and it is possible to execute the sticking or puncture at a desired position by using a positioning member, but when moving the sticking portion, there is a fear that a mis-sticking into the front side of the foramen ovale valve will occur caused by a body movement which happens in the case of a shallow level of anesthesia. It is preferable or perhaps ideal to select the sticking position to be right under the position at which the foramen ovale valve and the atrial septum secundum overlap, but it is extremely difficult to adjust by hand the position of the needle member of the stick portion, which is positioned at the distal tip of the fine long catheter.